It is generally known to mount rubber blankets on transfer cylinders, which are also called rubber blanket cylinders. Typically, the ends of the rubber blanket are inserted into the tensioning channels or cylinder pits of the transfer cylinder and fixed in place. To minimize the channel width, recently rubber blankets have been used that consist of a multi-layer structure. The layers include a cover layer that can be inked and that can contact a print carrier (e.g., a paper web) for transferring a print image. In addition, compressible layers and non-expandable layers are used. The compressible layers can be materials with air inclusions and the non-expandable layers are typically woven cloth or textile layers. It is advantageous to arrange a non-expandable layer underneath the printing cover layer and to arrange a compressible layer underneath the non-expandable layer. However, other layer sequences can also be used. Multiple compressible and non-expandable layers can also be used.
With known rubber printing blankets having rigid carrier plates (which are referred to as metal backed rubber blankets), there is a risk that individual layers may detach from the carrier plate during the printing process due to forces in the channel region if only the ends not that are not covered by the rubber layer structure are inserted into the cylinder channel. In particular, there is the risk that the printing cover layer will separate.
A printing blanket is disclosed in DE 101 17 409 A1 that has a rubber layer of consisting of several layers and where at least one end of the rubber blanket is sealed. The seal extends through the entire material thickness of the rubber layer structure and also partially covers the free ends of the metal layer or carrier plate introduced into the cylinder pit due to its somewhat triangular cross section. This arrangement, in particular, prevents fluids from penetrating the textile intermediate layer or from causing a separation of the topmost layer by getting under the topmost layer during the printing process. Due to extreme stresses or very high forces on the rubber blanket ends, the seal can be damaged leading to separation of individual layers. This can considerably shorten the life of such rubber blankets in comparison to conventional rubber blankets that do not have rigid carrier layers.